Pulling a Subtree from an existing git

The project has subdirectories sub-1, sub-2, sub-3. The first should be its own repository, but should also retain its own history.

First, we extract its history as an independent item, and make that into a seprate branch.

1git subtree split --prefix=sub-1 -b sub

If you want …

Check out the sample hooks:

1cd $GIT_REPO
2ls .git/hooks
3head .git/hooks/pre-commit.sample

Add a hook to check the shell scripts in $GIT_REPO before making a commit:

1echo '#!/bin/sh
2shellcheck *.sh' > .git/hooks/commit-msg
3chmod u+x .git/hooks/commit-msg

Committing

Your git hooks will not enter the …

Install, and add with

1git lfs install

Then track some filetype with:

1git lfs track "\*.ttf"

Or a directory with:

1git lfs track "images/"

All changes require adding .gitattributes.

This utility is largely useless, as it can only identify people by their email. So if someone has multiple GPG keys associated with one email, the tool will not work.

A broken tool is better than a tool which will break soon.

• Setup
• Extras

The vim-gnupg plugin lets vim edit gpg-encrypted files as if they were unencrypted.

It's probably in your package manager. If not, you'll need to endure the faff of following the instructions.

Making keys

Generate keys:

1gpg --full-generate-key

Follow the guide.

Encrypting a file

1gpg -r malinfreeborn@posteo.net -e file

-r specifies the recipient.

Check you have an encrypted version of your file.

Changing Expiration Dates

1gpg --list-keys
2# or...
3gpg -k

... and then use the second part of 'pub', which is …

Basic Documents

Great a file called name.ms, with the following content:

1.TL
2Groff-Time
3.AU
4Ghost
5.NH
6How to Format Groff Documents.
7.PP
8Groff needs two new lines to show a new paragraph.

Then make a pdf from the document with:

groff -ems name.ms -Tpdf > name.pdf

The commands must be placed at the start of a …

A hard link is one file which exists in multiple locations.

Each file has an ID, which is kept on the hard disk's partition. Each hard link has the same ID, because they are the same file. This ID is called the 'inode'.

Create a file, and a hard link:

1fortune > $file_1
2mkdir -p x/y/z/
3ln $file_1 x/y/z/$file_2 …

Convert jpg to png.

1convert image.jpg image.png

1convert image.jpg -quality 50 image.jpg

'Quality' must be from 1 to 100.

1convert -resize 50% image.jpg image2.jpg

Resizing only changes jpegs. Change a png with:

1convert input.png png8:out.png

Invert Colours

1convert input.jpg output.jpg -negate

Make Images Smaller

1 …